Added W3Schools resource about ES6 (#2332)

content/roadmaps/100-frontend/content/103-javascript/103-es6-and-modular-javascript.md

@@ -4,6 +4,7 @@ ECMAScript 2015 or ES2015 is a significant update to the JavaScript programming
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink badgeText='Read' colorScheme="yellow" href='https://www.javascripttutorial.net/es6/'>ES6 Tutorial</BadgeLink>
+<BadgeLink badgeText='Read' colorScheme="yellow" href='https://www.w3schools.com/js/js_es6.asp'>W3Schools: Javascript ES6</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=NCwa_xi0Uuc'>Learn Modern JavaScript in 1 Hour</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=nZ1DMMsyVyI'>JavaScript ES6, ES7, ES8</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=3PHXvlpOkf4'>Build 15 JavaScript Projects - Vanilla JavaScript</BadgeLink>